Research in normal and disordered phonology requires measures of speech production that are biolinguistically appropriate and psychometrically robust. A number of speech and prosody-voice measures have specifically been developed for use in genetic studies and in other descriptive studies of developmental phonological disorders. These 10 metrics of articulation competence in conversational speech, which are obtained from a 5-10 minute conversational speech sample, have been evaluated in terms of reliability and life span reference data, and form part of a clinical classification instrument titled the Speech Disorders Classification System (SDCS). This classification includes a number of descriptive subtypes, including individuals without speech disorders, those whose speech disorders have normalized, and, among those with developmental phonological disorders, subgroupings into speech delayed individuals and those with persistent, residual errors persisting beyond the ninth year, with other refinements possible. These metrics have been obtained for members of nuclear families ascertained through a preschool child with a severe phonologic disorder. Current efforts focus on comparisons of these metrics and subtypes with other standard measures of speech and language. Commingling analyses of these measures in children from families ascertained through a preschool child with a language disorder showed no evidence that a mixture of distributions, rather than a single distribution, provided a better fit to the data.[unreadable]